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MG MGA - Judson driving me crazy

I am in the process of trying to get my Judson working. The unit is as new from George Folchi. The first carb I had kept flooding, and George was truly magnificent in his response and has replaced it with great speed.

The new carb does not flood, but otherwise exhibits the same problems as the other one:

I static timed to about 8 degrees, which is where the car ran beautifully on the SUs.

When the engine starts (which it will only do with a couple of pumps on the pedal, and FULL choke, even when hot), it stumbles for a few seconds as it thinks what it wants to do, and then becomes a screamer, RPM shooting straight off the top of the redline. Nothing will control it, I have backed off the idle, made sure the carb butterfly valve is closed, made sure that the mix screw is only 1.5 turns out.

I have replaced the points and condensor, no change
I also replaced the plugs to try and improve starting, no change (BP6ES, copper core)

George has suggested I check for air leaks in the inlet manifold, nothing. The vacuum is so strong there that there is condensation on the outside of the manifold.

All joints appear to be tight. The SC will not run at all unless on full choke. Putting the choke in causes the car to stop, even when all is hot.

Please help, otherwise I will have to take it all off again tomorrow night as I should be driving to Italy on Thursday morning.

Dominic
dominic clancy

The supercharger will start rough..I have to pump the gas twice and it kicks over but no power. I have to let it stand for about 15-30 seconds till the engine clears of excess oil and gas. Then the power and response comes on. If you have to run the choke it would seen you have an air leak. In order for the sc to SCREAM without any pressure on the gas pedal, ask yourself how is the engine getting gas to run like that. Have you used carb cleaner to see if you have any leaks by spraying it on the joints to see if there is a difference in RPM. The points and timing should not make the difference you are talking about. I set my timing at 28 degree @ 3000rpm , I have no knock or ping. Hope this helps. There is also a guy on your side of the pond in Belgium that is like George over here. You should be able to find him in the archive. Good Luck.!!!
JEFF BECKER

Dominic,

Try stronger Return springs on the carb.
Sounds like it's just sucking the butterfly open.

Not much of an expert with supercharging, my brother wants to fit a Toyota MR2 one to his MKII.. I keep telling him to leave my engine alone...

Hope this helps...

Cheers <MARK>
Mark Hester

As an MG OWNER/SHADY TREE MECHANIC of some 40+ years, I suggest you purchase and screw in a "COLOURTUNE TRANSPARENT INSULATOR TUNING SPARK PLUG" that lets you ACTUALLY "LOOK INTO YOUR COMBUSTION CHAMBER" and "SEE" WHAT COLOR YOUR AIR/FUEL RATIO IS BURNING, (IF they can STILL BE FOUND!) ORANGE is TOO RICH, WHITE is TOO LEAN. It should be some shade of BLUE! LIGHT BLUE for max GAS MILEAGE & SMOG REDUCTION, DARK BLUE for MORE POWER. ORANGE is OK when the CHOKE is in operation. I used to have two of these screwed into #1 & #4 SPARK PLUG HOLES, and they were great for REALLY "SYNCHING DUAL CARBS"! Screwed into #2 & #3 SPARK PLUG HOLES, you can "SEE" how MGA's (& MGB's) "SIAMESED PORTS" screw up the mixture slightly on an "UNMODIFIED HEAD" and how a REALLY GOOD "MODIFIED HEAD/exhaust SYSTEM" betters the air/fuel ratio!
wattswh1

It was a vacuum leak.

next the carb return spring broke, fixed. I drove to work, and stopped en route to increase the idle speed, found that the idle screw had fallen out. Apart from that the car ran fine (apart from needing some gas to stop it stalling) to and from work (about 12km each way), till I started up the mountain, as I got home, where it started to cough and bang like crazy. It will idle, (with an idle screw replaced but not run. Sigh.

I,m letting it cool down, and will then go and diagnose. I've rented a car online to go to Italy...
dominic clancy

This thread was discussed between 26/07/2005 and 27/07/2005

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